Bug or bad UI design?

I just downloaded the game to play it again after a LONG time of playing it last and decided to try out the alternative simulacrum mode. After selecting the character and clicking execute it takes me to another window where I can select loadout etc. I had a look through there, didn’t change anything and clicked the “Ready” button but nothing happens.

I don’t know why the ready button does nothing? I can’t tell if it’s because of a bug stopping me from being able to play or maybe something I didn’t unlock yet or even if it’s something to do with the new expansion. There is no popup or anything saying why the giant green ready button does nothing.

If it is indeed something to do with the expansion then why does the game not tell me this instead of nothingness, it seems like a pretty awful design for newer players such as myself who spent 10 mins trying to figure out why the button does nothing and even trying out other game modes to see if the button works there (it does in single player). Just tell me I need the expansion to play this mode!!!

If it’s not something to do with the expansion then I have re-installed it twice and still can’t get it to work, I have no idea what’s going on.

Any advice? Thanks in advance.